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J C Meunier

Publications and source records attributed to J C Meunier.

At least 55 records · Page 3Linked to original sources
PubMed1997

Autoradiographic localization of [3H]nociceptin binding sites from telencephalic to mesencephalic regions of the mouse brain.

The binding sites of [3H]nociceptin (also named Orphanin FQ), the endogenous ligand of the ORL1 (opiate receptor like 1) receptor, were localized in the central nervous system of the mouse using an autoradiographic procedure. A high density of binding sites was seen in the cerebral cortex, paraventricular nucleus of the thalamus, amygdaloid complex, suprachiasmatic nucleus, medial thalamus and medial geniculate nucleus. Moderate binding was observed in the nucleus accumbens, lateral septum, lateral thalamus, hippocampus, periaqueductal grey matter and pons. Finally, low levels of binding were seen in the striatum, olfactory tubercle, hypothalamus and substantia nigra. Thus, it appears that the ORL1 receptor is particularly abundant in the cerebral cortex and limbic system of the mouse brain.

Amygdala↗
PubMed1997

Recognition and activation of the opioid receptor-like ORL 1 receptor by nociceptin, nociceptin analogs and opioids.

Nociceptin, also known as orphanin FQ, was recently identified as the naturally occurring agonist of orphan opioid receptor-like ORL1 receptor (Meunier et al., 1995, Nature 377, 532; Reinscheid et al., 1995, Science 270, 792). Nociceptin is a heptadecapeptide which, although it resembles dynorphin A, the endogenous agonist of the kappa-opioid receptor, displays very low potency in competing with binding of [3H]diprenorphine to or inhibiting adenylate cyclase via mu-, delta- and kappa-opioid receptors. Tritium-labeled nociceptin ([3H]nociceptin) was used here to establish a pharmacological profile in vitro of the ORL 1 receptor. In membranes from recombinant Chinese hamster ovary (CHO) cells expressing the ORL 1 receptor, equilibrium binding of [3H]nociceptin is highly specific, saturable (Bmax in the range 1.3-1.8 pmol/mg protein) and of high affinity (Kd approximately equal to 0.1 nM). It is selectively decreased in the presence of Na+ ions and/or of the GTP analog 5'-guanylylimido-diphosphate, an allosteric regulation that is analogous to that of opiate binding to opioid receptors. A few opiates, namely lofentanil, a 4-anilinopiperidine derivative and etorphine, a 6,14-endo-ethenotetrahydrothebaine derivative, were found to be quite potent not only in competing with binding of [3H]nociceptin at the ORL 1 receptor but also in inhibiting forskolin-induced accumulation of cyclic AMP in intact recombinant CHO cells. In a preliminary attempt to delineate active parts of the neuropeptide, nociceptin analogs were also tested, including N- and C-terminal truncation products. Our results suggest that the highly basic, internal core of nociceptin might be essential in conferring on the peptide both affinity for and activity at the ORL 1 receptor. In this respect, the message and address division of dynorphin A, nociceptin's closest structural analog, do not seem to apply to nociceptin.

Adenylyl Cyclase Inhibitors↗
PubMed1997

Orphan neuropeptide NocII, a putative pronociceptin maturation product, stimulates locomotion in mice.

NocII is a heptadecapeptide whose sequence lies immediately downstream of nociceptin, the newly discovered natural agonist of the ORL1 receptor, in pronociceptin, nociceptin's precursor polypeptide. Since the sequence of NocII is framed by putative convertase excision sites and it totally conserved across murine and human species, we have sought to determine whether this orphan neuropeptide might by physiologically significant, i.e. endowed with central biological activity in vivo. Intracerebroventricular administration of 10 and 100 ng of NocII increased locomotion in mice. However, unlike nociceptin, which stimulates both the horizontal and vertical (rearing) components of locomotion, NocII affected only the horizontal component. The motor stimulant action of NocII appears to depend largely on dopamine transmission since it is totally reversed by the D1 or the D2 dopamine receptor antagonists SCH 23390 and haloperidol. NocII does not modify the number of explored holes in the hole board test, indicating that, unlike nociceptin, the orphan peptide does not affect exploratory behavior in mice.

Amino Acid Sequence↗
PubMed1997

Cloning of the gene encoding the catalytic subunit of casein kinase II from the yeast Yarrowia lipolytica.

Casein kinase II from the yeast Yarrowia lipolytica is a heterotetramer of the form alpha alpha' beta 2. We report on the cloning and sequencing of a partial cDNA and of the complete genomic DNA coding for the catalytic alpha subunit of the casein kinase II from this yeast species. The sequence of the gene coding for this enzyme has been analyzed. No intron was found in the gene, which is present in a single copy. The deduced amino acid sequence of the gene shows high similarity with those of alpha subunit described in other species, although, uniquely, Y. lipolytica CKII alpha lacks cysteines. We find that the alpha subunit sequence of Y. lipolytica CKII is shown greater homology with the corresponding protein from S. pombe than with that from S. cerevisiae. We have analyzed CKII alpha expression and CKII alpha activity. We show that expression of this enzyme is regulated. The catalytic subunit is translated from a single mRNA, and the enzyme is present at a very low level in Y. lipolytica, as in other yeasts.

Amino Acid Sequence↗
PubMed1997

Purification and characterization of a type 2A protein phosphatase from Yarrowia lipolytica grown on a phosphate-deficient medium.

Intracellular protein phosphatase activity has been identified in the yeast Yarrowia lipolytica. This activity was maximal early in its exponential growth phase, and it was enhanced by Pi-deficiency of the culture medium. On a Pi-deficient medium, the major protein phosphatase was purified. This enzyme was dissociated with 80% ethanol treatment, its activity was slightly increased (30%) with heparine and largely enhanced (1.5 to 3-fold) with polycations. This enzyme could be classified as a type 2A protein phosphatase. It is composed of a catalytic subunit and other subunits. Its optimum pH value is 7.2, the apparent Km for casein is 37 microM and the apparent velocity 3.6 pmol hydrolyzed32 Pi min-1 pmol-1 enzyme.

Catalysis↗
PubMed1997

Characterization of truncated forms of hepatitis C virus glycoproteins.

Hepatitis C virus (HCV) glycoproteins (E1 and E2) both contain a carboxy-terminal hydrophobic region, which presumably serves as a membrane anchor. When they are expressed in animal cell cultures, these glycoproteins, in both mature complexes and misfolded aggregates, are retained in the endoplasmic reticulum. The effect of carboxy-terminal deletions on HCV glycoprotein secretion and folding was examined in this study. Sindbis and/or vaccinia virus recombinants expressing truncated forms of these glycoproteins ending at amino acids 311, 330, 354 and 360 (truncated E1), and 661, 688, 704 and 715 (truncated E2) were constructed. When expressed using Sindbis virus vectors, only truncated forms of E1 and E2 ending at amino acids 311 (E1t311) and 661 (E2t661), respectively, were efficiently secreted. Analysis of secretion of truncated forms of E2 glycoprotein expressed by vaccinia viruses indicated that significant secretion was still observed for a protein as large as E2t715. However, only secreted E2t661 appeared to be properly folded. Secreted HCV glycoprotein complexes were also detected in the supernatant of cell culture when E1t311 and E2t661 were coexpressed. Nevertheless, these secreted complexes, as well as E1t311 expressed alone, were misfolded. The effect of coexpression of E1 and E2 glycoproteins on each other's folding was evaluated with the help of a conformation-sensitive monoclonal antibody (for E2) or by analysing intramolecular disulfide bond formation (for E1). Our data indicate that the folding of E2 is independent of E1, but that E2 is required for the proper folding of E1.

Animals↗
PubMed1996

Nociceptin stimulates locomotion and exploratory behaviour in mice.

The recently characterized heptadecapeptide nociceptin, the endogenous agonist of the orphan opioid receptor-like 1 (ORL1 receptor), has been tested for its effects on locomotion and exploratory behaviour in mice. I.c.v. administration of as little as 10 ng of nociceptin/animal stimulated locomotor activity. This effect was dose-dependent, increasing in intensity up to 100 ng and in duration for doses in the range of 1000-10000 ng. The stimulation of horizontal locomotion elicited by 100 ng nociceptin was accompanied by a stimulation of the vertical component of locomotion. These effects were not reversed by high doses (1.5 and 4.5 mg/kg s.c.) of the opioid receptor antagonist naloxone. Increasing doses of the dopamine D2 receptor antagonist haloperidol (0.1-0.5 mg/kg i.p.) as well as of the dopamine D1 receptor antagonist SCH 23390 [R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine hydrochloride] (0.0075-0.03 mg/kg s.c.) reversed this effect, suggesting that nociceptin exerts its motor-stimulant actions by increasing central dopaminergic transmission. Nociceptin was also found to increase the number of head dips in the hole-board test, indicating that the peptide stimulates exploratory behaviour.

Animals↗
PubMed1996

Replacement of Gln280 by His in TM6 of the human ORL1 receptor increases affinity but reduces intrinsic activity of opioids.

The ORL1 (Opioid Receptor-Like) receptor is the G protein-coupled receptor whose amino acid sequence is closest to those of opioid receptors. Residues that are conserved in ORL1 and the three types of opioid receptor, but also a residue, His in the sixth putative transmembrane (TM6) helix, which is present in all opioid receptor types but absent in ORL1, appear to play a key role in receptor recognition and/or activation. Here we have sought to create an opioid binding pocket in the non-opioid ORL1 receptor by replacing residue Gln280 in its TM6 by the corresponding His residue of opioid receptors. The mutation affects neither the affinity of nociceptin - the natural ORL1 agonist - for the receptor, nor the potency of nociceptin to inhibit adenylyl cyclase via ORL1. In contrast, we find that a few opioid ligands, the agonists lofentanil, etorphine and dynorphin A, and especially the antagonists diprenorphine and nor-BNI, bind the mutant Q280H receptor with substantially (5- to > 100-fold) higher apparent affinity than they do the wild-type receptor. Moreover, lofentanil and etorphine no longer act as pure agonists, as they do at the native ORL1 receptor, but are endowed with clear antagonist properties at the mutant receptor. The mutation Q280H, which increases affinity while decreasing intrinsic activity of opioids at ORL1, emphasizes the importance of the His residue for opioid recognition and activation.

Adenylyl Cyclase Inhibitors↗
PubMed1996

Structure, tissue distribution, and chromosomal localization of the prepronociceptin gene.

Nociceptin (orphanin FQ), the newly discovered natural agonist of opioid receptor-like (ORL1) receptor, is a neuropeptide that is endowed with pronociceptive activity in vivo. Nociceptin is derived from a larger precursor, prepronociceptin (PPNOC), whose human, mouse, and rat genes we have now isolated. The PPNOC gene is highly conserved in the three species and displays organizational features that are strikingly similar to those of the genes of preproenkephalin, preprodynorphin, and preproopiomelanocortin, the precursors to endogenous opioid peptides, suggesting the four genes belong to the same family-i.e., have a common evolutionary origin. The PPNOC gene encodes a single copy of nociceptin as well as of other peptides whose sequence is strictly conserved across murine and human species; hence it is likely to be neurophysiologically significant. Northern blot analysis shows that the PPNOC gene is predominantly transcribed in the central nervous system (brain and spinal cord) and, albeit weakly, in the ovary, the sole peripheral organ expressing the gene. By using a radiation hybrid cell line panel, the PPNOC gene was mapped to the short arm of human chromosome 8 (8p21), between sequence-tagged site markers WI-5833 and WI-1172, in close proximity of the locus encoding the neurofilament light chain NEFL. Analysis of yeast artificial chromosome clones belonging to the WC8.4 contig covering the 8p21 region did not allow to detect the presence of the gene on these yeast artificial chromosomes, suggesting a gap in the coverage within this contig.

Amino Acid Sequence↗
PubMed1995

Isolation and structure of the endogenous agonist of opioid receptor-like ORL1 receptor.

The ORL1 receptor, an orphan receptor whose human and murine complementary DNAs have recently been characterized, structurally resembles opioid receptors and is negatively coupled with adenylate cyclase. ORL1 transcripts are particularly abundant in the central nervous system. Here we report the isolation, on the basis of its ability to inhibit the cyclase in a stable recombinant CHO(ORL1+) cell line, of a neuropeptide that resembles dynorphin A9 and whose amino acid sequence is Phe-Gly-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln. The rat-brain cDNA encodes the peptide flanked by Lys-Arg proteolytic cleavage motifs. The synthetic heptadecapeptide potently inhibits adenylate cyclase in CHO(ORL1+) cells in culture and induces hyperalgesia when administered intracerebroventricularly to mice. Taken together, these data indicate that the newly discovered heptadecapeptide is an endogenous agonist of the ORL1 receptor and that it may be endowed with pro-nociceptive properties.

Amino Acid Sequence↗
PubMed1995

Dual specificity of casein kinase II from the yeast Yarrowia lipolytica.

In the case of protein kinases, and especially in the case of casein kinase II (CKII), a link has been found between the type of the amino acids autophosphorylated and the targeted amino acids on the substrates. In the presence of Mg2+, CKII from the yeast Yarrowia lipolytica is autophosphorylated on serines and threonines, and a serine threonine kinase activity is found predominantly when casein is used as substrate. In the presence of Mn2+, CKII autophosphorylation is inhibited on serines, and autophosphorylation on tyrosines, negligible in the former case, becomes significant. Tyrosine phosphorylation is then found to occur on casein. Mn2+ transforms CKII into a protein kinase with dual specificity, shifting its specificity from serine/threonine kinase towards a serine/threonine and tyrosine kinase. Mn2+ decreases the level of serine and threonine phosphorylation observed, while on the other hand promoting tyrosine kinase activity.

Casein Kinase II↗
PubMed1994

ORL1, a novel member of the opioid receptor family. Cloning, functional expression and localization.

Selective PCR amplification of human and mouse genomic DNAs with oligonucleotides encoding highly conserved regions of the delta-opioid and somatostatin receptors generated a human DNA probe (hOP01, 761 bp) and its murine counterpart (mOP86, 447 bp). hOP01 was used to screen a cDNA library from human brainstem. A clone (named hORL1) was isolated, sequenced and found to encode a protein of 370 amino acids whose primary structure displays the seven putative membrane-spanning domains of a G protein-coupled membrane receptor. The hORL1 receptor is most closely related to opioid receptors not only on structural (sequence) but also on functional grounds: hORL1 is 49-50% identical to the murine mu-, delta- and kappa-opioid receptors and, in CHO-K1 cells stably transfected with a pRc/CMV:hORL1 construct, ORL1 mediates inhibition of adenylyl cyclase by etorphine, a 'universal' (nonselective) opiate agonist. Yet, hORL1 appears not to be a typical opioid receptor. Neither is it a somatostatin or sigma (N-allylnormetazocine) receptor. mRNAs hybridizing with synthetic oligonucleotides complementary to mOP86 are present in many regions of the mouse brain and spinal cord, particularly in limbic (amygdala, hippocampus, septum, habenula, ...) and hypothalamic structures. We conclude that the hORL1 receptor is a new member of the opioid receptor family with a potential role in modulating a number of brain functions, including instinctive behaviours and emotions.

Amino Acid Sequence↗
PubMed1994

Chronic morphine induces tolerance and desensitization of mu-opioid receptor but not down-regulation in rabbit.

Tolerance to chronic morphine treatment was studied in adult rabbits and modifications in the number and the state of coupling of the mu-opioid receptors were investigated in the cerebellum. Tolerance was induced by the subcutaneous injection of progressively increasing doses of morphine (5-100 mg/kg/injection) over 6 days and its occurrence was controlled by a nociceptive test: electrical stimulation of the dental pulp. At the end of the treatment, the rabbits were tolerant to the analgesic effects of morphine and the tolerance phenomenon correlated well with a significant decrease in the adenylate cyclase inhibition (approximately 60%). The functional uncoupling between the enzyme and the mu-opioid receptor was accompanied neither by a decrease in the number of high affinity receptors measured by equilibrium binding techniques (Kd = 0.19 +/- 0.03 in control vs. 0.11 +/- 0.04 nM in tolerant animals; Bmax = 322 +/- 62 vs. 362 +/- 58 fmol/mg of protein), nor by a modification of the physical coupling between the receptor and its G-protein. It can be concluded that desensitization, under our experimental conditions, can be clearly distinguished from down-regulation.

Adenylyl Cyclase Inhibitors↗
PubMed1994

SK-N-BE: a human neuroblastoma cell line containing two subtypes of delta-opioid receptors.

A human neuroblastoma cell line, SK-N-BE, was shown to express a substantial amount of opioid receptors (200-300 fmol/mg of protein). A ligand binding profile of these receptors revealed that they could belong to two distinct subtypes of delta-opioid receptors. Results from sucrose-gradient sedimentation experiments were compared with similar data obtained with the mu-opioid receptor of the rabbit cerebellum and the delta-opioid receptor of the hybrid NG108-15 cell line and have shown that the opioid receptor of the SK-N-BE cell line behaved hydrodynamically as an intermediate between mu- and delta-opioid receptors. Taken together, pharmacological and hydrodynamic studies suggest that the opioid receptors present in the SK-N-BE cell membranes could belong to two delta-opioid receptor subtypes interacting allosterically. Functional experiments suggest that at least one of these subtypes of delta-opioid receptor is negatively coupled to the adenylate cyclase via a Gi protein and that the opiate receptors of the SK-N-BE neuroblastoma cell line undergo a rapid down-regulation when preincubated in the presence of the high-affinity opioid, etorphine.

Adenylyl Cyclases↗
PubMed1993

Staining technique for phosphatases in polyacrylamide gels.

The described staining technique affords a means to detect and evaluate directly on the electrophoresis polyacrylamide gel the activity of phosphatases present in complex extracts or in purified solutions, in particular phosphatases requiring alkaline pH for optimum activity, e.g. fructose bisphosphatase, sedoheptulose bisphosphatase, and alkaline phosphatase, and 5'-nucleotidase. The method is based on a modified malachite green procedure determining orthophosphate released by the specific enzyme reactions carried out in the gel and leads to the formation of sharp blue-green-colored bands on a pale blue background. Staining intensity is proportional to the amount of Pi formed. The lower limit of phosphate detection was in the order of 0.2 nmol. This method provides a routine tool for comparative studies of biochemical properties and isozymic composition of phosphatases from diverse sources.

5'-Nucleotidase↗
PubMed1992

The delta-opioid receptor in neuroblastoma x glioma NG 108-15 hybrid cells is strongly precoupled to a G-protein.

Neuroblastoma x glioma NG 108-15 hybrid cells contain a homogeneous population of delta-opioid receptors. NG 108-15 membranes were labelled either with the opiate agonist, [3H]etorphine or the opiate antagonist [3H]diprenorphine under various conditions: absence or presence of Na+ and/or 5'-guanylylimidophosphate (GppNHp). Ultracentrifugation in linear sucrose gradients after digitonin solubilization of prelabeled receptor was performed. In the soluble extracts from NG 108-15 hybrid cell membranes, bound [3H]etorphine and bound [3H]diprenorphine sedimented in the same position, even in the presence of NaCl and/or GppNHp. These data were analyzed in terms of relative agonist potency of diprenorphine on this specific model, using equilibrium binding studies and inhibition of adenylate cyclase activity. Diprenorphine, at the concentrations used for sedimentation studies, behaving as an opiate antagonist, it is concluded that the delta-opioid receptor could be strongly precoupled to the G-protein in the NG 108-15 cell.

Adenylyl Cyclase Inhibitors↗